What Is The Remedy For Irregular Periods?

I am female of 34 years and this is first time my periods get suddenly stopped. After consulting doctor, she has given me cyclopam for 4 days. I have completed this course before 2 days and still I do not get my periods. What's the problem, I have already taken Pregnancy Test, they are negative twice. I am facing back pain. One of the stopping of periods I guess is sudden increase in weight since last month. Please guide me what can I do now, what is reaction time of medicine doctor given to me. What are the side effects of this medicine as I do not want to take them. How can I make my periods normal from next month. I already started workouts and control my diet plan for loosing weight. Please help me!